(a) Field of the Invention
This inventive concept relates generally to semiconductor techniques, and more specifically, to a microphone and its manufacturing method.
(b) Description of the Related Art
Microphone basically is a capacitance-based sound transmission device, it measures the pressure a sound wave generated when traveling through air or liquid and converts it into an electric signal. A basic Micro Electro Mechanical System (MEMS) microphone comprises a solid vibration film plate and a back plate. Incoming sound wave causes deformation on the vibration film plate, which in turn causes a change of capacitance of a flat panel capacitor.
To ensure effective reception of a sound wave, the vibration film plate need to be made very thin, which, however, makes it susceptible to damage. Sound waves with a large amplitude may fracture the vibration film as a result of large-amplitude oscillations of the film. With ever increasing demand for the acoustic devices that work in a wide power range, a microphone with high acoustic tolerance as demonstrated in Air Pressure Test (APT), a test that evaluates the acoustic tolerance of a microphone, is increasingly desirable.